Alterations in renal function occur in patients with chronic liver disease due to a process not as yet well understood. These alterations range from changes in solute excretion to complete failure of renal function in the so called "hepatorenal syndrome". Many aspects of this phenomenon have been studied and etiologic factors suggested include the production of abnormal humoral substances, the lack of removal of normal substances and the stimulation of the hepatic nerves. Therapy of these renal abnormalities is clearly hampered by lack of understanding of the precise changes involved. The proposed study offers a systematic approach to the detection of early changes in renal function due to liver failure in a series of animal models.